Unable to get the otWhiteboard_update Signal from Host to other participant

Question

I'm trying to use the opentok Whiteboard functionality.

Scenario: As a participant in the session, I cannot catch the otWhiteboard_update signal from the host who initiated the Whiteboard operation.

https://github.com/aullman/opentok-whiteboard/blob/master/demo.html

OT.checkSystemRequirements = function () {
            return true;
        };
        angular.module('demo', ['opentok', 'opentok-whiteboard'])
        .controller('DemoCtrl', ['$scope', 'OTSession', function ($scope, OTSession) {
            $scope.connected = false;
            OTSession.init('YOUR_API_KEY', 'YOUR_SESSION_ID', 'YOUR_TOKEN', function (err) {
                if (!err) {
                    $scope.$apply(function () {
                        $scope.connected = true;
                    });
                }
            });
        }]);

• Do I have to publish the OTSession?
• Do I have to connect the OTSession?
• Do the other participants in the session have to subscribe to the OT Session stream (which is not available now)?

Please help me with this implementation. I tried a lot, but nothing works; I'm clueless :(